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    SubjectRE: [PATCH 05/10] iommu/ioasid: Create an IOASID set for host SVA use
    Date
    > From: Jacob Pan <jacob.jun.pan@linux.intel.com>
    > Sent: Thursday, March 26, 2020 1:55 AM
    >
    > Bare metal SVA allocates IOASIDs for native process addresses. This
    > should be separated from VM allocated IOASIDs thus under its own set.

    A curious question. Now bare metal SVA uses the system set and guest
    SVA uses dynamically-created set. Then do we still allow ioasid_alloc
    with a NULL set pointer?

    >
    > This patch creates a system IOASID set with its quota set to PID_MAX.
    > This is a reasonable default in that SVM capable devices can only bind
    > to limited user processes.
    >
    > Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
    > ---
    > drivers/iommu/intel-iommu.c | 8 +++++++-
    > drivers/iommu/ioasid.c | 9 +++++++++
    > include/linux/ioasid.h | 9 +++++++++
    > 3 files changed, 25 insertions(+), 1 deletion(-)
    >
    > diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
    > index ec3fc121744a..af7a1ef7b31e 100644
    > --- a/drivers/iommu/intel-iommu.c
    > +++ b/drivers/iommu/intel-iommu.c
    > @@ -3511,8 +3511,14 @@ static int __init init_dmars(void)
    > goto free_iommu;
    >
    > /* PASID is needed for scalable mode irrespective to SVM */
    > - if (intel_iommu_sm)
    > + if (intel_iommu_sm) {
    > ioasid_install_capacity(intel_pasid_max_id);
    > + /* We should not run out of IOASIDs at boot */
    > + if (ioasid_alloc_system_set(PID_MAX_DEFAULT)) {
    > + pr_err("Failed to enable host PASID allocator\n");
    > + intel_iommu_sm = 0;
    > + }
    > + }
    >
    > /*
    > * for each drhd
    > diff --git a/drivers/iommu/ioasid.c b/drivers/iommu/ioasid.c
    > index 6265d2dbbced..9135af171a7c 100644
    > --- a/drivers/iommu/ioasid.c
    > +++ b/drivers/iommu/ioasid.c
    > @@ -39,6 +39,9 @@ struct ioasid_data {
    > static ioasid_t ioasid_capacity;
    > static ioasid_t ioasid_capacity_avail;
    >
    > +int system_ioasid_sid;
    > +static DECLARE_IOASID_SET(system_ioasid);
    > +
    > /* System capacity can only be set once */
    > void ioasid_install_capacity(ioasid_t total)
    > {
    > @@ -51,6 +54,12 @@ void ioasid_install_capacity(ioasid_t total)
    > }
    > EXPORT_SYMBOL_GPL(ioasid_install_capacity);
    >
    > +int ioasid_alloc_system_set(int quota)
    > +{
    > + return ioasid_alloc_set(&system_ioasid, quota, &system_ioasid_sid);
    > +}
    > +EXPORT_SYMBOL_GPL(ioasid_alloc_system_set);
    > +
    > /*
    > * struct ioasid_allocator_data - Internal data structure to hold information
    > * about an allocator. There are two types of allocators:
    > diff --git a/include/linux/ioasid.h b/include/linux/ioasid.h
    > index 8c82d2625671..097b1cc043a3 100644
    > --- a/include/linux/ioasid.h
    > +++ b/include/linux/ioasid.h
    > @@ -29,6 +29,9 @@ struct ioasid_allocator_ops {
    > void *pdata;
    > };
    >
    > +/* Shared IOASID set for reserved for host system use */
    > +extern int system_ioasid_sid;
    > +
    > #define DECLARE_IOASID_SET(name) struct ioasid_set name = { 0 }
    >
    > #if IS_ENABLED(CONFIG_IOASID)
    > @@ -41,6 +44,7 @@ int ioasid_register_allocator(struct ioasid_allocator_ops
    > *allocator);
    > void ioasid_unregister_allocator(struct ioasid_allocator_ops *allocator);
    > int ioasid_attach_data(ioasid_t ioasid, void *data);
    > void ioasid_install_capacity(ioasid_t total);
    > +int ioasid_alloc_system_set(int quota);
    > int ioasid_alloc_set(struct ioasid_set *token, ioasid_t quota, int *sid);
    > void ioasid_free_set(int sid, bool destroy_set);
    > int ioasid_find_sid(ioasid_t ioasid);
    > @@ -88,5 +92,10 @@ static inline void ioasid_install_capacity(ioasid_t total)
    > {
    > }
    >
    > +static inline int ioasid_alloc_system_set(int quota)
    > +{
    > + return -ENOTSUPP;
    > +}
    > +
    > #endif /* CONFIG_IOASID */
    > #endif /* __LINUX_IOASID_H */
    > --
    > 2.7.4

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